SEDIMENT CARPET 61 



thus easily reduce its total thickness by 40' r or even 

 more. The second factor is possible variations in the 

 rate of sedimentation which may have occurred during 

 the enormous span of time involved. For several reasons 

 it is highly probable that our present epoch is one of 

 abnormally intense continental erosion and rapid sub- 

 marine sedimentation, or in other words that the growth 

 in thickness of the sediment carpet in bygone ages went 

 on at a considerably slower rate than at present. These 

 two circumstances may well increase the time required 

 for accumulating the sediment layer measured by 

 WeibuU by a factor of 2 or 3, if not even more. 



At any rate, it is evident that the age of the particular 

 part of the Atlantic Ocean where these great thicknesses 

 were found must be counted in many millions of years. 

 This appears to knock the bottom out of the famous 

 "continental drift'' theory of Wegener, according to 

 which the Atlantic Ocean should have begun to open 

 up in Cretaceous time, that is, 60 to 80 million years 

 ago. 



The explanation for the much lower figures found in 

 the other oceans is even more far-fetched. They cannot 

 well indicate a lesser age of the oceans in question, but 

 may instead be due to a much lower rate of sedimenta- 

 tion. In fact there are certain indications that at least 

 in the central parts of the Pacific Ocean the accumula- 

 tion of red clay proceeds at a rate about ten times slower 

 than in the central Atlantic. 



There is, however, another circumstance which may 



